1. Field of the invention
The present invention relates to a recording apparatus for recording characters, images, and other information on a recording material, and a recording head of an ink jet type mounted on such apparatus used for information processing systems, such as a copying machine, a facsimile equipment, a printer, a word processor, and a personal computer. In this respect, recording includes the provision of ink or the like (such as printing, image formation, print, coloring) with respect to all the ink supporting elements such as cloth, thread, paper, and sheet materials. The present invention is applicable not only to the field of information processing, but also, to the wide industrial fields including the apparel industry, which use cloth, thread, paper, sheet materials, and other ink supporting elements.
2. Related Background Art
It has been in practice that an ink jet recording apparatus for recording on paper, cloth, plastic sheet, OHP sheet, and other recording medium (hereinafter, may also be referred to simply as a recording sheet) is made capable of performing its highly densified recording at high speeds. Therefore, the ink jet recording apparatus is utilized and sold on the market as output means of information processing systems, such as a copying machine, a facsimile equipment, an electronic typewriter, a word processor, or a printer serving as an output terminal of a work station, or a handy or portable printer provided for a personal computer, a host computer, an optical disk device, or a video equipment. In such a case, the ink jet recording apparatus is structured to comply with the function and mode of usage inherent to each of those devices.
In general, an ink jet recording apparatus comprises a carriage having recording means (recording head) and an ink tank mounted on it, conveying means for conveying a recording sheet, and a controlling means for controlling the carriage and sheet conveying means. Then, the recording head that discharges ink droplets from a plurality of discharge ports is caused to serially scan in the direction (main scanning direction) orthogonal to the conveying direction of a recording sheet, while the recording sheet is fed intermittently for an amount equivalent to the recording width of the sheet when recording is at rest. Here, this method is arranged to perform recording by discharging ink onto the recording sheet in accordance with recording signals. Since its running costs are low, this method is used widely. Also, it is used as a quiet recording method. Further, by use of the head having many numbers of nozzles arranged for discharging ink on the straight line in the sub-scanning direction, it is possible to record on the recording sheet by one scanning of the head on the sheet in a width corresponding to such numbers of nozzles at a time. As a result, it is possible to attain the recording operation at a higher speed.
Further, in a case of an ink jet recording apparatus for color recording, color images are formed by superposing ink droplets discharged from the recording heads for use of plural colors. It is generally assumed that when a color recording is performed, three or four kinds of recording heads and ink cartridge are required including the three prime colors, yellow (Y), magenta (M), and cyan (C) or these three colors plus black (B). In recent years, there has been on the practical use an apparatus having these three- or four-color recording heads mounted on it to form images in full color.
Here, in order to make it easier to understand the conventional technique and the present invention, the description will be made of the structural outline of the ink jet recording head generally in use.
The conventional ink jet recording head is structured by putting together the electrothermal transducing elements formed on a silicon substrate, ink discharge ports for use of recording also formed on such silicon substrate, ink paths each having the thermoactive portion in such electrothermal transducing element, and a ceiling plate having a recess to form a common liquid chamber for supplying ink to each of such ink paths as disclosed in Japanese Patent Laid-Open Application No. 55-132253.
FIG. 8 is a sectional perspective view which schematically illustrates the structure of an ink jet recording head.
The recording head 230 is formed by the ceiling 231 and the substrate 232. The ceiling plate 231 is provided with a plurality of grooves 233 that form nozzles serving as ink paths, a large grooved portion 234 serving as the common liquid chamber conductively connected with these grooves, and a supply inlet aperture 235 for supplying ink to such common liquid chamber. Also, the substrate 232 is integrally formed with electrothermal transducing elements 236 each corresponding to the respective nozzle, and each of the electrodes 237 to supply electric power to the respective electrothermal transducing element by the application of film formation technology. Such ceiling plate 231 and substrate 232 are connected to form a plurality of discharge ports (orifices) 238 for discharging ink.
Also, in the ink jet recording head structured as described above, drivers are incorporated to drive the electrothermal transducing elements arranged on the substrate.
Further, in the case of an ink jet recording head for use of color recording, ink jet recording heads each for use of different color are arranged in parallel as an ink jet unit as shown in FIG. 9.
However, when the conventional ink jet recording head as described above, particularly the one for color recording, is used, the space occupied by the recording head becomes larger by several times the space occupied by the head for use of monochromatic recording, because a plurality of recording heads, each for different color, are arranged in parallel. As a result, it is difficult to comply with the users's request that a color printer should be made smaller at lower costs, among others. As a countermeasure, therefore, a proposal is made to the effect that a plurality of common liquid chambers are provided by use of the ceiling plate, hence supplying ink of different color to each of the common liquid chambers thus arranged for performing color recording by use of one recording head. In this case, when a plurality of common liquid chambers are arranged in one and the same recording head, the structure should be arranged in order to separate the common liquid chambers from each other assuredly. For that matter, Therefore, use of sealing material is attempted when separating the plural common chambers. In order words, grooves (separation grooves) are formed on each portion that part one common liquid chamber from another in order to fill in the sealing material. When the ceiling plate and the substrate are connected together, the sealing material is filled in each of such grooves. In this case, the separation grooves are formed along each of the ink paths from the respective common liquid chamber to the ink discharge nozzle. Therefore, it is necessary to prevent the sealing material from flowing into each of the ink paths. For example, if the amount of sealing material to be filled in is too much, there is a fear that the sealing material overflows to block the ink paths. Also, if the filling amount of the sealing material is too small, the separation of the common liquid chambers becomes imperfect. Thus, there is a fear that ink in each of the common liquid chambers is mixed. To prevent ink from being mixed, there is a need for careful considerations that should be given in detail as to the filling amount and filling speed of the sealing material. However, should the sealing material be filled with such care, it invites significant increase of operating time manufacturing costs inevitably.